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The quality deterioration in minimally processed fruits and vegetables is partly attributed to the rates of respiration and ethylene production.   Mild heat treatment of whole apples inhibits protein synthesis, ethylene production and fruit softening, but enhances respiration.    The effects of heat treatments on biosynthesis of carbon dioxide and ethylene production in cut Pacific Rose apples have not been studied.  Pacific Rose is a new apple cultivar developed by HortResearch that has a pleasant sugar/acid balance and a firm and crisp texture, ideal characteristics for minimal processing.

The objective of this study was to determine the effects of different heat treatments of Pacific Rose apple discs on the rates of respiration and ethylene production.

A mild heat treatment of 45^oC was sufficient to inhibit most of the ethylene production 6 hrs after cutting, while a heat treatment at 65-70^oC was required to inhibit respiration.

The mean respiration rate for raw apple discs, 6 hrs after cutting was 17.88 ml/kg/hr.  Water logging due to immersion in distilled water, seems to have an inhibitory effect on the respiration rate as seen by the control sample (mean respiration rate 11.35 ml/kg/hr).  The respiration rates for samples heat-treated between 40^oC and 55^oC varied from 11.39 – 13.45 ml/kg/hr and rapidly decreased to 8.40 ml/kg/hr at 60^oC and to 1.65 ml/kg/hr at 70^oC.

The rate of ethylene production in cut apple samples seems to be enhanced by water logging.  The rate of ethylene production after a heat treatment at 40^oC was similar to that of the control, but it decreased significantly with increase in temperature from 45^oC to 65^oC, when the rate decreased to 0.65 μl/kg/hr. 

This indicates that mild heat treatments of Pacific Rose apple can produce significant decreases in the respiration and ethylene production rates, which could influence the shelf life of minimally processes products.